#pragma GCC optimize(3, "unroll-loops", "no-stack-protector")
#define atsum(l, r) accumulate(l, r, 0)
#include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/hash_policy.hpp>
using namespace std;
using ll = long long;
using ull = unsigned long long;
constexpr int inf = 0x3f3f3f3f;
constexpr ll INF = 0x3f3f3f3f3f3f3f3f;
template <typename T>
inline void chkmin(T &x, T y) {
    x = min(x, y);
}
template <typename T>
inline void chkmax(T &x, T y) {
    x = max(x, y);
}
namespace FastIO {
// ------------------------------
#define IN_HAS_NEG
#define OUT_HAS_NEG
#define CHK_EOF
#define DISABLE_MMAP
// ------------------------------
#if __cplusplus < 201400
#error Please use C++14 or higher.
#endif
#if __cplusplus > 201700
#define INLINE_V inline
#else
#define INLINE_V
#endif
#if (defined(LOCAL) || defined(_WIN32)) && !defined(DISABLE_MMAP)
#define DISABLE_MMAP
#endif
#ifndef DISABLE_MMAP
#include <sys/mman.h>
#endif
#ifdef LOCAL
inline char gc() { return getchar(); }
inline void pc(char c) { putchar(c); }
#else
#ifdef DISABLE_MMAP
INLINE_V constexpr int _READ_SIZE = 1 << 18;
INLINE_V static char _read_buffer[_READ_SIZE], *_read_ptr = nullptr,
                                               *_read_ptr_end = nullptr;
inline char gc() {
    if (__builtin_expect(_read_ptr == _read_ptr_end, false)) {
        _read_ptr = _read_buffer;
        _read_ptr_end =
            _read_buffer + fread(_read_buffer, 1, _READ_SIZE, stdin);
#ifdef CHK_EOF
        if (__builtin_expect(_read_ptr == _read_ptr_end, false)) return EOF;
#endif
    }
    return *_read_ptr++;
}
#else
INLINE_V static const char *_read_ptr =
    (const char *)mmap(nullptr, INT_MAX, 1, 2, 0, 0);
inline char gc() { return *_read_ptr++; }
#endif
INLINE_V constexpr int _WRITE_SIZE = 1 << 18;
INLINE_V static char _write_buffer[_WRITE_SIZE], *_write_ptr = _write_buffer;
inline void pc(char c) {
    *_write_ptr++ = c;
    if (__builtin_expect(_write_buffer + _WRITE_SIZE == _write_ptr, false)) {
        fwrite(_write_buffer, 1, _write_ptr - _write_buffer, stdout);
        _write_ptr = _write_buffer;
    }
}
INLINE_V struct _auto_flush {
    ~_auto_flush() {
        fwrite(_write_buffer, 1, _write_ptr - _write_buffer, stdout);
    }
} _auto_flush;
#endif
#ifdef CHK_EOF
inline bool _isdigit(char c) { return (c & 16) && c != EOF; }
inline bool _isgraph(char c) { return c > 32 && c != EOF; }
#else
inline bool _isdigit(char c) { return c & 16; }
inline bool _isgraph(char c) { return c > 32; }
#endif
template <class T>
INLINE_V constexpr bool _is_integer = numeric_limits<T>::is_integer;
template <class T>
INLINE_V constexpr bool _is_signed = numeric_limits<T>::is_signed;
template <class T>
INLINE_V constexpr bool _is_unsigned = _is_integer<T> && !_is_signed<T>;
template <>
INLINE_V constexpr bool _is_integer<__int128> = true;
template <>
INLINE_V constexpr bool _is_integer<__uint128_t> = true;
template <>
INLINE_V constexpr bool _is_signed<__int128> = true;
template <>
INLINE_V constexpr bool _is_unsigned<__uint128_t> = true;
#undef INLINE_V
inline void read(char &c) {
    do c = gc();
    while (!_isgraph(c));
}
inline void read_cstr(char *s) {
    char c = gc();
    while (!_isgraph(c)) c = gc();
    while (_isgraph(c)) *s++ = c, c = gc();
    *s = 0;
}
inline void read(string &s) {
    char c = gc();
    s.clear();
    while (!_isgraph(c)) c = gc();
    while (_isgraph(c)) s.push_back(c), c = gc();
}
#ifdef IN_HAS_NEG
template <class T, enable_if_t<_is_signed<T>, int> = 0>
inline void read(T &x) {
    char c = gc();
    bool f = true;
    x = 0;
    while (!_isdigit(c)) {
        if (c == 45) f = false;
        c = gc();
    }
    if (f)
        while (_isdigit(c)) x = x * 10 + (c & 15), c = gc();
    else
        while (_isdigit(c)) x = x * 10 - (c & 15), c = gc();
}
template <class T, enable_if_t<_is_unsigned<T>, int> = 0>
#else
template <class T, enable_if_t<_is_integer<T>, int> = 0>
#endif
inline void read(T &x) {
    char c = gc();
    while (!_isdigit(c)) c = gc();
    x = 0;
    while (_isdigit(c)) x = x * 10 + (c & 15), c = gc();
}
inline void write(char c) { pc(c); }
inline void write_cstr(const char *s) {
    while (*s) pc(*s++);
}
inline void write(const string &s) {
    for (char c : s) pc(c);
}
#ifdef OUT_HAS_NEG
template <class T, enable_if_t<_is_signed<T>, int> = 0>
inline void write(T x) {
    char buffer[numeric_limits<T>::digits10 + 1];
    int digits = 0;
    if (x >= 0) do
            buffer[digits++] = (x % 10) | 48, x /= 10;
        while (x);
    else {
        pc(45);
        do buffer[digits++] = -(x % 10) | 48, x /= 10;
        while (x);
    }
    while (digits) pc(buffer[--digits]);
}
template <class T, enable_if_t<_is_unsigned<T>, int> = 0>
#else
template <class T, enable_if_t<_is_integer<T>, int> = 0>
#endif
inline void write(T x) {
    char buffer[numeric_limits<T>::digits10 + 1];
    int digits = 0;
    do buffer[digits++] = (x % 10) | 48, x /= 10;
    while (x);
    while (digits) pc(buffer[--digits]);
}
template <int N>
struct _tuple_io_helper {
    template <class... T>
    static inline void _read(tuple<T...> &x) {
        _tuple_io_helper<N - 1>::_read(x), read(get<N - 1>(x));
    }
    template <class... T>
    static inline void _write(const tuple<T...> &x) {
        _tuple_io_helper<N - 1>::_write(x), pc(32), write(get<N - 1>(x));
    }
};
template <>
struct _tuple_io_helper<1> {
    template <class... T>
    static inline void _read(tuple<T...> &x) {
        read(get<0>(x));
    }
    template <class... T>
    static inline void _write(const tuple<T...> &x) {
        write(get<0>(x));
    }
};
template <class... T>
inline void read(tuple<T...> &x) {
    _tuple_io_helper<sizeof...(T)>::_read(x);
}
template <class... T>
inline void write(const tuple<T...> &x) {
    _tuple_io_helper<sizeof...(T)>::_write(x);
}
template <class T1, class T2>
inline void read(pair<T1, T2> &x) {
    read(x.first), read(x.second);
}
template <class T1, class T2>
inline void write(const pair<T1, T2> &x) {
    write(x.first), pc(32), write(x.second);
}
template <class T1, class... T2>
inline void read(T1 &x, T2 &...y) {
    read(x), read(y...);
}
template <class... T>
inline void read_cstr(char *x, T *...y) {
    read_cstr(x), read_cstr(y...);
}
template <class T1, class... T2>
inline void write(const T1 &x, const T2 &...y) {
    write(x), write(y...);
}
template <class... T>
inline void write_cstr(const char *x, const T *...y) {
    write_cstr(x), write_cstr(y...);
}
template <class T>
inline void print(const T &x) {
    write(x);
}
inline void print_cstr(const char *x) { write_cstr(x); }
template <class T1, class... T2>
inline void print(const T1 &x, const T2 &...y) {
    print(x), pc(32), print(y...);
}
template <class... T>
inline void print_cstr(const char *x, const T *...y) {
    print_cstr(x), pc(32), print_cstr(y...);
}
inline void println() { pc(10); }
inline void println_cstr() { pc(10); }
template <class... T>
inline void println(const T &...x) {
    print(x...), pc(10);
}
template <class... T>
inline void println_cstr(const T *...x) {
    print_cstr(x...), pc(10);
}
}  // namespace FastIO
using namespace FastIO;
template <typename T>
inline void clear(T &x) {
    T y;
    swap(x, y);
}
const int N = 110;
int tab[N];
struct DS {
    ull a, b;
    int cnt[N];
    inline void ins(int x) {
        if (!(cnt[x]++)) {
            if (x < 64)
                a |= 1ull << x;
            else
                b |= 1ull << x - 64;
        }
    }
    inline void del(int x) {
        if (!(--cnt[x])) {
            if (x < 64)
                a ^= 1ull << x;
            else
                b ^= 1ull << x - 64;
        }
    }
    inline int min() { return a ? __lg(a & -a) : __lg(b & -b) + 64; }
    inline int max() { return b ? __lg(b) + 64 : __lg(a); }
    inline int calc() { return tab[max()] - tab[min()]; }
} T[N];
mt19937_64 rng(random_device{}());
int n, k, a[N], id[N];
ull val[N];
int bl[N];
ll curans, BEST;
inline void SA() {
    for (int i = 1; i <= n; i++)
        T[i].a = T[i].b = 0, memset(T[i].cnt, 0, sizeof(T[i].cnt));
    for (int i = 1; i <= n; i++) id[i] = i, val[i] = rng();
    shuffle(id + 1, id + k + 1, rng);
    sort(a + 1, a + n + 1, [](int x, int y) { return val[x] < val[y]; });
    int curi = 1;
    // cerr << "find qwq:" << a[1] << ' ' << a[2] << ' ' << a[3] << ' ' << a[4] << endl;
    for (int i = 1; i <= n; i++) {
        bl[i] = id[curi++];
        T[bl[i]].ins(a[i]);
        if (curi > k) {
            curi = 1;
        //     shuffle(id + 1, id + k + 1, rng);
        }
    }
    // for (int i = 1; i <= n; i++) cerr << bl[i] << ' ' << a[i] << endl;
    // sleep(1);
    curans = 0;
    for (int i = 1; i <= k; i++) curans += tab[T[i].max()] - tab[T[i].min()];
    chkmin(BEST, curans);
    // cerr << curans << endl;
    // sleep(1);
    for (double TEM = 3000; TEM > 1e-3; TEM *= 0.995) {
        int x = rng() % n + 1, y = rng() % n + 1;
        if (bl[x] == bl[y] || a[x] == a[y]) continue;
        if (T[bl[x]].cnt[a[y]] || T[bl[y]].cnt[a[x]]) continue;
        ll reans = curans;
        reans -= T[bl[x]].calc() + T[bl[y]].calc();
        T[bl[x]].del(a[x]), T[bl[y]].del(a[y]);
        T[bl[y]].ins(a[x]), T[bl[x]].ins(a[y]);
        swap(bl[x], bl[y]);
        reans += T[bl[x]].calc() + T[bl[y]].calc();
        // cerr << T[1].calc() << ' ' << T[2].calc() << ' ' << T[3].calc() << ' ' << curans << endl;
        if (reans < curans)
            curans = reans;
        else if ((long double)(rng()) / ULLONG_MAX <= exp((curans - reans) / TEM))
            curans = reans;
        else {
            T[bl[x]].del(a[x]), T[bl[y]].del(a[y]);
            T[bl[y]].ins(a[x]), T[bl[x]].ins(a[y]);
            swap(bl[x], bl[y]);
        }
        chkmin(BEST, curans);
    }

}
int resp[N];
int main() {
    freopen("diyiti.out", "w", stdout);
    freopen("diyiti.in", "r", stdin);
    BEST = INF;
    read(n, k);
    for (int i = 1; i <= n; i++) read(a[i]), tab[i] = a[i];
    sort(tab + 1, tab + n + 1);
    for (int i = 1; i <= n; i++)
        a[i] = lower_bound(tab + 1, tab + n + 1, a[i]) - tab, ++resp[a[i]];
    for (int i = 1; i <= n; i++)
        if (resp[i] > k) return println(-1), 0;
    int rc = 0;
    while (double(clock()) / CLOCKS_PER_SEC < 1.35) SA(), ++rc;
    println(BEST);
    return 0;
}